1. Field of the Invention
This invention relates to an indicator, and more particularly to an indicator such as a speedmeter or a tachometer used in motor vehicle, which has an ultraviolet lamp for illuminating indicia, such as scales and numerals arranged on a scale plate of the indicator, containing fluorescent brightener therein for visibility improvement.
2. Description of the Prior Art
One type of prior art indicator, such as a speedmeter or a tachometer for use in motor vehicles, includes an ultraviolet lamp for illuminating indicia, such as scales or numerals, that contain fluorescent brightener therein. In such a conventional indicator, the fluorescent brightener emits visible light when the indicia receive ultraviolet light. Therefore, the luminance of the indicia is good when the ultraviolet lamp is on, which makes the indicia especially visible in the night-time.
However, in the conventional indicator, the fluorescent brightener is simply added directly to the indicia on the scale plate. Therefore, the design of the scale plate, namely the visible arrangement of the indicia in the indicator does not change even if the ultraviolet lamp is turned on or off.